package org.apache.solr.schema;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.text.Collator;
import java.text.ParseException;
import java.text.RuleBasedCollator;
import java.util.Locale;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute;
import org.apache.lucene.collation.CollationKeyAnalyzer;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.TermRangeQuery;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.Version;
import org.apache.lucene.analysis.util.ResourceLoader;
import org.apache.solr.common.SolrException;
import org.apache.solr.common.SolrException.ErrorCode;
import org.apache.solr.response.TextResponseWriter;
import org.apache.solr.search.QParser;

/**
 * Field for collated sort keys. These can be used for locale-sensitive sort and
 * range queries.
 * <p>
 * This field can be created in two ways:
 * <ul>
 * <li>Based upon a system collator associated with a Locale.
 * <li>Based upon a tailored ruleset.
 * </ul>
 * <p>
 * Using a System collator:
 * <ul>
 * <li>language: ISO-639 language code (mandatory)
 * <li>country: ISO-3166 country code (optional)
 * <li>variant: vendor or browser-specific code (optional)
 * <li>strength: 'primary','secondary','tertiary', or 'identical' (optional)
 * <li>decomposition: 'no','canonical', or 'full' (optional)
 * </ul>
 * <p>
 * Using a Tailored ruleset:
 * <ul>
 * <li>custom: UTF-8 text file containing rules supported by RuleBasedCollator
 * (mandatory)
 * <li>strength: 'primary','secondary','tertiary', or 'identical' (optional)
 * <li>decomposition: 'no','canonical', or 'full' (optional)
 * </ul>
 * 
 * @see Collator
 * @see Locale
 * @see RuleBasedCollator
 * @since solr 4.0
 */
public class CollationField extends FieldType {
	private Analyzer analyzer;

	@Override
	protected void init(IndexSchema schema, Map<String, String> args) {
		properties |= TOKENIZED; // this ensures our analyzer gets hit
		setup(schema.getResourceLoader(), args);
		super.init(schema, args);
	}

	/**
	 * Setup the field according to the provided parameters
	 */
	private void setup(ResourceLoader loader, Map<String, String> args) {
		String custom = args.remove("custom");
		String language = args.remove("language");
		String country = args.remove("country");
		String variant = args.remove("variant");
		String strength = args.remove("strength");
		String decomposition = args.remove("decomposition");

		final Collator collator;

		if (custom == null && language == null)
			throw new SolrException(ErrorCode.SERVER_ERROR,
					"Either custom or language is required.");

		if (custom != null
				&& (language != null || country != null || variant != null))
			throw new SolrException(
					ErrorCode.SERVER_ERROR,
					"Cannot specify both language and custom. "
							+ "To tailor rules for a built-in language, see the javadocs for RuleBasedCollator. "
							+ "Then save the entire customized ruleset to a file, and use with the custom parameter");

		if (language != null) {
			// create from a system collator, based on Locale.
			collator = createFromLocale(language, country, variant);
		} else {
			// create from a custom ruleset
			collator = createFromRules(custom, loader);
		}

		// set the strength flag, otherwise it will be the default.
		if (strength != null) {
			if (strength.equalsIgnoreCase("primary"))
				collator.setStrength(Collator.PRIMARY);
			else if (strength.equalsIgnoreCase("secondary"))
				collator.setStrength(Collator.SECONDARY);
			else if (strength.equalsIgnoreCase("tertiary"))
				collator.setStrength(Collator.TERTIARY);
			else if (strength.equalsIgnoreCase("identical"))
				collator.setStrength(Collator.IDENTICAL);
			else
				throw new SolrException(ErrorCode.SERVER_ERROR,
						"Invalid strength: " + strength);
		}

		// set the decomposition flag, otherwise it will be the default.
		if (decomposition != null) {
			if (decomposition.equalsIgnoreCase("no"))
				collator.setDecomposition(Collator.NO_DECOMPOSITION);
			else if (decomposition.equalsIgnoreCase("canonical"))
				collator.setDecomposition(Collator.CANONICAL_DECOMPOSITION);
			else if (decomposition.equalsIgnoreCase("full"))
				collator.setDecomposition(Collator.FULL_DECOMPOSITION);
			else
				throw new SolrException(ErrorCode.SERVER_ERROR,
						"Invalid decomposition: " + decomposition);
		}
		// we use 4.0 because it ensures we just encode the pure byte[] keys.
		analyzer = new CollationKeyAnalyzer(Version.LUCENE_40, collator);
	}

	/**
	 * Create a locale from language, with optional country and variant. Then
	 * return the appropriate collator for the locale.
	 */
	private Collator createFromLocale(String language, String country,
			String variant) {
		Locale locale;

		if (language != null && country == null && variant != null)
			throw new SolrException(ErrorCode.SERVER_ERROR,
					"To specify variant, country is required");
		else if (language != null && country != null && variant != null)
			locale = new Locale(language, country, variant);
		else if (language != null && country != null)
			locale = new Locale(language, country);
		else
			locale = new Locale(language);

		return Collator.getInstance(locale);
	}

	/**
	 * Read custom rules from a file, and create a RuleBasedCollator The file
	 * cannot support comments, as # might be in the rules!
	 */
	private Collator createFromRules(String fileName, ResourceLoader loader) {
		InputStream input = null;
		try {
			input = loader.openResource(fileName);
			String rules = IOUtils.toString(input, "UTF-8");
			return new RuleBasedCollator(rules);
		} catch (IOException e) {
			// io error
			throw new RuntimeException(e);
		} catch (ParseException e) {
			// invalid rules
			throw new RuntimeException(e);
		} finally {
			IOUtils.closeQuietly(input);
		}
	}

	@Override
	public void write(TextResponseWriter writer, String name, IndexableField f)
			throws IOException {
		writer.writeStr(name, f.stringValue(), true);
	}

	@Override
	public SortField getSortField(SchemaField field, boolean top) {
		return getStringSort(field, top);
	}

	@Override
	public Analyzer getAnalyzer() {
		return analyzer;
	}

	@Override
	public Analyzer getQueryAnalyzer() {
		return analyzer;
	}

	/**
	 * analyze the range with the analyzer, instead of the collator. because jdk
	 * collators might not be thread safe (when they are its just that all
	 * methods are synced), this keeps things simple (we already have a
	 * threadlocal clone in the reused TS)
	 */
	private BytesRef analyzeRangePart(String field, String part) {
		TokenStream source;

		try {
			source = analyzer.tokenStream(field, new StringReader(part));
			source.reset();
		} catch (IOException e) {
			throw new RuntimeException(
					"Unable to initialize TokenStream to analyze range part: "
							+ part, e);
		}

		TermToBytesRefAttribute termAtt = source
				.getAttribute(TermToBytesRefAttribute.class);
		BytesRef bytes = termAtt.getBytesRef();

		// we control the analyzer here: most errors are impossible
		try {
			if (!source.incrementToken())
				throw new IllegalArgumentException(
						"analyzer returned no terms for range part: " + part);
			termAtt.fillBytesRef();
			assert !source.incrementToken();
		} catch (IOException e) {
			throw new RuntimeException("error analyzing range part: " + part, e);
		}

		try {
			source.end();
			source.close();
		} catch (IOException e) {
			throw new RuntimeException(
					"Unable to end & close TokenStream after analyzing range part: "
							+ part, e);
		}

		return BytesRef.deepCopyOf(bytes);
	}

	@Override
	public Query getRangeQuery(QParser parser, SchemaField field, String part1,
			String part2, boolean minInclusive, boolean maxInclusive) {
		String f = field.getName();
		BytesRef low = part1 == null ? null : analyzeRangePart(f, part1);
		BytesRef high = part2 == null ? null : analyzeRangePart(f, part2);
		return new TermRangeQuery(field.getName(), low, high, minInclusive,
				maxInclusive);
	}
}
